1. Field of the Invention
This invention relates to sunscreen compositions, and, more particularly, to such compositions containing an additive ingredient to boost the SPF rating of a UV-B active therein.
2. Description of the Prior Art
Sunscreen compositions generally contain an active ingredient to absorb UV-B irradiation of wavelengths from 280 to 320 nm, which can cause erythema burning of the skin. Such compositions also may contain actives that absorb UV-A irradiation of wavelengths from 320 to 400 nm. These agents protect sensitive skin from harmful effects. These active sunscreen compounds (and the active amounts thereof) generally are selected to provide a desired sun protection factor (SPF). This SPF rating is expressed mathematically by the ratio of the irradiation time required to attain the erythema-forming threshold with the UV screening agent present to the time required to attain the same threshold in the absence of the UV screening agent.
An active sunscreen agent which absorbs irradiation in the UV-B range generally contributes much of the SPF rating to a sunscreen composition. Thus, high SPF values ordinarily are obtained by incorporating a large amount of a UV-B absorbing sunscreen compound therein, e.g., octylmethoxy cinnamate and benzophenone-3. However, addition of such compounds in such large quantities can cause skin irritancy as well as increase the cost of the formulation.
Accordingly, it is an object of this invention to provide a sunscreen composition which includes an additive ingredient which boosts the SPF rating of the composition.
Another object herein is to provide sunscreen compositions which require less UV-B compound to achieve a desired SPF rating for the composition
Still another object of this invention to provide a sunscreen composition including a phenylethyl or benzyl ester compound which boosts the SPF rating of the composition.